Control means for draft regulators



June 4, 1946. M, w REW 2,401,553

CONTROL MEANS FOR DRAFT REGULATORS Filed June 50, 1943 2 Sheets-Sheet lINVENTOR. ffb/PE/S 1M CREW I4 W I Patented June 4, 1946 CONTROL DIEANSFOR DRAFT REGULATORS Morris W. Crew, Cleveland, Ohio, assignor to TheHotstream Heater Company, Cleveland, Ohio,

a corporation of Ohio Application June 30, 1943, Serial No. 492,840

3 Claims. (01. 236-45) This invention relates to the control of thedraft in the operation of magazine feed stoves or other forms af solidfuel fired furnaces, boilers or space heating equipment.

One object of the invention is to provide an improved draft controlleror regulator which is thermostatically controlled in such manner as toautomatically limit the rate of combustion and the stack temperature andthus prevent overheating or unnecessary fuel loss.

Another object is to provide an improved thei mostatically controlleddraft regulator capable of adjustment to meet any desired temperatureconditions, within reasonable limits.

Still another object is to provide a combined draft regulator andcontroller in which all parts, including the control parts, may beassembled and sold as a complete unit ready for insertion in orattachment to the usual stove pipe connection to the stack.

A further object is to provile a draft control hereinafter. i

In the drawings, which represent one typical embodiment of theinvention,

Fig. 1 is a front elevation, showing only a portlton of the stove towhich the regulating unit is connected;

Fig. 2 is a side elevation, from the left in Fig. 1.;

Fig. 3 is a sectional elevation on the line 3-3, Fig.

Fig. 4 is a detail sectional elevation on the line 4-4, Fig. 5;

Fig. 5 is a detail sectional plan view on the line 5--5, Fig. 4;

Fig. 6 is a sectional elevation on the 1ine 6--5, Fig. 2, showing theflutter closed; and

Fig. '7 is a similar view, showing the flutter open.

In the drawings It represents conventionally the top portion of anysuitable furnace, boiler or stove, preferably fired by coal or othersolid fuel, with which the draft regulating or control unit of thepresent invention may be used. For example, it may be a magazine feedstove of the general form shown in Patent No. 2,255,527, grantedSeptember 9, 1941, to Sam P. Locke, although other forms of stove may beemployed. In the arrangement shown the products'of combustion or fluegases leave the stove by way of an opening in its upper portion towhichis connected the pipe or conduit II for conducting such ases to thechimney or stack (not shown) or to the outer atmosphere. The regulatingor control unit of the present invention is attached to or forms a partof the said conduit.

Said unit, in the arrangement sh'own, includes a stove pipe T 12 havin arunning section [3 and a lateral section 14 providing three open endedarms a, b, 0, designed for connection oftwo of them tothe stove andstack respectively, with the third open to atmosphere to provide checkdraft where desirable or necessary.

In the third arm referred to, here marked. c, is located a draftregulator of suitable form consisting of a disc or plate for flutter 15,mounted to pivot or swing at 1-6 in a, thimblelike frame I! and providedwith a counterweight l 8. The flutter of course oscillates back andforth between the dotted line position and the full line positionagainst stop Ila, Fig. 6, to balance out fluctuations and varying draftpull from the chimney or stack. The pipe and the particular draftregulator used with any stove will be chosen or selected of the propersiZe and the counterweight l8 will be of the proper calibrated weight toproduce the requisite-draft for the desired maximum rating andefliciency, Which in the case of a stove of the type shown may beassumed to require a draft of, say, .04 inch. The counterweight is thuscarefully calibrated at the factory to produce that draft, and inoperation at maximum output the stove will produce an attendant stacktemperature of 850 to 900 F.

The present invention provides means by which the draft automaticallymay be reduced when desirable,such as during mild weather or when forany reason the stove might continue to operate at maximum output whenthat is undesirable.

As shown, the control unit includes a thermostatic element, such as abimetallic strip or member 19, one end of which is fastened to a member28 pivoted at 2] on a bracket 22, and the other end of which carries anarm 23 pinned at 24 to 1 a rod 25 sliding through and guided in anopenture below normal in the space to be heated, such as the roomcontaining the stove. The parts then occupy the positions shown in Fig.6, with the bimetallic strip holding the rod 25 away from the closedflutter J5. When the fire is started in the stove combustion and draftincrease untilthe, stove is operating at maximum output with the desireddraft of .04 inch. Heat transfer from the stove to the space :to beheated is rapid. The temperature of the fiue gases and stack reaches 850to 900 F. and the temperature in the thermostat chamber em slightlylesser value, it being understood, however, that at all times there is adefinite relation betweenthe temperatures of the flue gases and inchamber 3!. However, at first and until the room temperature comes up tonormal, say 72 F., the temperature in chamber 3| does not risesufficiently to move the end of rod 25 into the zone of movement offlutter I5.

During the initial period, while the room temperature is rising, theflutter moves back and forth, either quickly, to counteract the effectsof gusts, due to back draft, or slowly to. balance out gradualfluctuations in draft pull, thus tending to maintain the desirablemaximum stack draft of .04 inch.

When, finally, theroom temperature reaches normal, say 72 F., the rateof absorption of heat by the space to be heated from the exposed heatedparts, including the stove jacket, the T IZand thermostat casing 21,etc., has been so reduced that the temperature of both the flue gasesand in chamber 3| rises, with the, result of flexing the bimetallicstrip I9 until it reaches the position of Fig. 7, with the end of rod 25Within the zone of movement of the flutter. If, at the time, the flutteris closed, rod 25 will engage it and move it to and hold it in theposition of Fig. 7,

whereas if it is already open, rod 25 will merely hold it there. Ineither case the check draft opening is open, air flow through the fuelbed is reduced and held to a low value, the combus-- tion rate isreduced and sooner or later the stove and stack temperatures are reducedbelow that attendant upon operation at maxmum rating, to-

wit, 850 to 900? F. Thus, after. the stove has been, operated atmaximum. output for a period sufficient, to bring the space temperatureup to the desired normal value, it, is thereafter operated withthermostatic control to maintain normal space temperature, withoutoverheating and avoiding unnecessary waste offuel.

- Means may be provided for adjusting the parts to secure and maintainany desired normal space temperature. In the arrangement shown, thismeans takes the form of a screw 32 threaded into the bracket 22 andhaving swiveled connection at 33 to the member 20 to which; the lowerend of the strip I9 is attached. The head 34 of the screw is exposed onthe outside of the casing 21 for manual adjustment. Stops 35, 36 limitthe amount of adjustment in bothdirections. As the screw is adjusted tothe right, Fig. 6, thenormal space temperature will be increased, aswill.

be readily understood.

Means is also provided for manually and releasably locking the flutterin its full open position. This comprises a hand lever 31 pivoted in abracket 38 on the thimble l1, and having two positions, shown in Figs. 6and 4 respectively. Fig. 6 is the normal position, when, the lever. isineffective and flutter I is permitted to have full and unrestrictedoperation, as before. de-

scribed. Fig. 4 illustrates the locking position 7 of the lever in whichits inner arm has engaged the shutter and holds it open. The check draftopening is now wide open and ultimately thestack draft may be reduced toas low as .005 inch. This lever is used when the stove is banked atnight and low draft is desirable. It does away with any necessity ofadjusting the air intake at the bottom of the stove.

Suitable means may be provided for releasably locking the hand lever ineither of the two positions to which it may be adjusted, such as a smallteat 39 piuiched out of the metal of the lever and adapted to engageeither of two depressions 4:0 in the supporting bracket for said lever.

Since all parts of the mechanism, including the flutter and its thimbleand the thermostatic device and its housing, are relatively permanentlyattached to the pipe T It, the controlling or regulating device hereinvolved may be, assembled as a complete unit on the bench, at thefactoryand so sold and shipped for use. stated, the pipe and fluttersizes are predetermined and the weight and location of the,counterweight are calibrated for the particularv size and style of,stove or heating device with which the control unit is to be used, so asto produce the desired stack draft, say .04 inch more or less, requiredfor maximum efficiency and output.

When the unit is installed in, the original setting up of the stove, thebimetallic element is adjusted to a permanent setting by the user, by aseries of trials, until the stove produces and main tains the desirednormal room or space'temperature. I justing screw 32 inwardly oroutwardly to set the angle or position of the bimetallic strip and thus.determine the amount of movement of arm 23 and rod 25 required beforerod 25 exerts a controlling effect upon the flutter I5. While anydesirable bimetallic. element may be employed, I have used one whichbegins to travel at 200 F. and which reaches its maximum travel atpossibly 800 or 900 of temperature within the T H. When the parts are soadjusted, if the stove is serving a comparatively small space that'maybe satisfactorily heated by utilizing onlya portion of the maximumoutput of the stove, satisfactory heating may be accomplished byadjusting the screw 31 all the way in, which carries the rod 25 closerto thefiutter and permits it to be opened when the stove temperaturereaches. 400 to 500 of temperature. When a larger space is being heatedthescrew is adjusted all the way out, permitting the stove to operate atmaximum output until the normal temperature of 72 is reached, afterwhich thethermostat takes over control and prevents the possibility ofthe. stove continuing to operate at maximum output and eitheroverheating the room space or unnec essarily wasting fuel.

What I claim is:

1. As an article of manufacture, a.se1f-=contained draft controlleradapted for insertion into a stove stack pipe, comprising a pipe Thaving threev arms, two for connection to the stove and stackrespectively, a flutter mounted for swinging motion in the third arm, ahousing mounted, on said T closely adjacent to said third arm, a

thermostatic element enclosed within said hous extending through thewalls of said housing and,

third arm and movable into and out of the path As before,

This is accomplished by moving the ad- 7 of movement of the flutter, anda manually operatable releasable looking lever for said flutter movablymounted on the third T arm and having two positions in one of which theflutter is free for full motion and. in the other of which said leverengages the flutter and holds it in fully open position, and means formaintaining said lever in either of its two positions.

2. As an article of manufacture, a self-contained draft controller,comprising a pipe T having upper and lower end arms and a middle arm,the lower end arm being connectable to a stove or the like and the upperend arm being connectable to the stack pipe for said stove or the like,a flutter mounted for swinging movement in said middle arm, a chamberedhousing mounted on the lower end arm exteriorly thereof and in planarcontact therewith, the chamber of said housing having no directcommunication with such lower end arm, thermostatic means mounted withinthe chamber of said housing and sensitive to variations in thetemperature of the flue gases passing through the pipe T, and meansmounted within said middle arm for movement into and out of the path ofmovement of the flutter, said last named means being operativelyconnected with said thermostatic means for operation thereby.

3. As an article of manufacture, a self-contained draft controller,comprising a pipe T having two end arms and a middle arm, one end armbeing connectable to a stove or the like and the other end arm beingconnectable to the stack pipe for said stove or the like, a fluttermounted for swinging movement in said middle :11 a housing carried byone of said arms exteriorly thereof, thermostatic means pivotallymounted in said housing and extending into said third arm, a push rod insaid third arm adjustably connected to said thermostatic means formovemerit into and out of the path of movement of the flutter, and meansconnected to said thermostatic means and extending to the outside of thehousing for adjusting said thermostatic means about its pivot to varythe range of temperature to which said thermostatic means is effectivelyresponsive.

MORRIS W. CREW.

